The service costs $14.99 a month, although people who sign up in April receive the service free for one month. The groundbreaking move has been anticipated since HBO Chief Executive Richard Plepler unveiled the service during an Apple product conference last month in San Francisco.

"This is a transformative moment for HBO, and we are excited to introduce HBO Now to all of you," Plepler said at that event.

The service marks the first time that HBO programming is being offered directly to consumers. Before now, people had to subscribe to a pay-TV package offered by a cable or satellite TV operator and then pay extra for HBO's premium channels.

The subscription service will offer 2,000 programming titles, including "Game of Thrones,""Girls," and "Silicon Valley." The launch was planned to coincide with the April 12 season premiere of "Game of Thrones."

HBO Now is aimed at attracting customers who do not currently subscribe to a pay-TV bundle but have high-speed Internet service. There are an estimated 10 million homes in the U.S. with broadband Internet service but no pay-TV.

The TV landscape has become increasingly competitive. Apple, in an effort to woo new customers, lowered the price of its Apple TV device to $69. Previously, the device cost consumers $99.